This invention relates to detecting mass addressing events. Examples of systems that can make use of this invention are telephone networks, addressable memory devices, data bus systems, and the like.
The detecting aspect of the invention relates to alerting a monitoring station of potential mass addressing events before such events happen. Such an aspect is particularly well suited for telephone networks wherein mass addressing events (within the telephone industry an "addressing event" being the dialing of a telephone number) can result in an enormous amount of non-revenue generating work for telephone service providers. Further, such overloads cause network instability by not only reducing throughput at a specific network element, but by also stressing the signaling network, databases, switches, and trunking network all at the same time.
The terms "mass addressing event" and "mass calling event" or the like are used herein to refer to addressing or calling events of sufficient magnitude to overload, overwhelm, shutdown, or damage conventional address routing circuitry. Telephone switching equipment, for example, often contains overload protection circuitry which will disable (e.g., shut down) individual switching devices if call volume exceeds a certain threshold rather than allowing switches to be damaged.
A mass calling event may be alternatively defined as a calling volume in excess of customer answering capability. Only very large telephone service customers are capable of answering more than 15 to 20 calls per second, most customers having substantially reduced capabilities. As such, call volumes in excess of 15-20 calls per second, while usually insufficient to overwhelm network switching circuitry, may nonetheless far exceed customer capability. Any calls in excess of customer capability go unanswered and cannot therefore be billed by telephone service providers (i.e., are non-revenue generating calls which reduce network throughput) and may be considered a form of mass calling event.
A classic example of a mass addressing event occurred during an episode of the television series Melrose Place when the viewing audience was invited to call a displayed telephone number to qualify for a chance to appear on a future episode. Switching networks received an estimated 20,000 calls per second in response to this promotion. Because of this calling volume, most attempted calls were uncompleted (as calling volume far exceeded customer answering capability), causing telephone service providers lost revenues. In general, during mass calling events of this nature, most attempted calls are uncompleted, necessarily reducing telephone service provider profits. Furthermore, such mass calling events may prompt switching network protection circuitry to shut down switching devices (to prevent the devices from being damaged), resulting in substantially reduced network capacity for all network customers (further reducing revenues to telephone service providers and fostering customer ill will). Clearly, from both a customer satisfaction viewpoint and a telephone service provider revenue viewpoint, mass addressing events are undesirable.
Conventional techniques for monitoring telephone networks and rerouting high calling volumes are not well suited for handling mass calling events. For example, U.S. Pat. No. 5,537,611 to Rajagopal et al. (hereinafter "the '611 patent") discloses using a database to collect and process traffic and routing statistics for special call processing services such as 800, 900, EVS, or VNET. Calling volumes can be monitored and alarms issued if calling volume exceeds preset thresholds within a one minute time interval. While the database disclosed in the '611 patent is well suited for dedicated networks with small calling volumes (calling volumes in the 4,000 to 5,000 calls per hour range are discussed, though the '611 patent indicates that an alarm threshold can be set between 1 and 65,000 calls per minute), such database systems are impractical for handling the calling volume (up to 20,000 calls per second or 1,200,000 calls per minute) experienced by a large telephone network during a mass calling event. The processing power and memory requirements needed to keep statistics on, to search through, and to update a database with so many telephone numbers makes use of the '611 patent's database impracticable during mass calling events.
One technique which can be adapted for handling mass calling events is disclosed in U.S. Pat. No. 5,450,483 to Williams (hereinafter "the '483 patent"). The '483 patent teaches a method of controlling overloads in a telephone network by monitoring the number of failed calls to a node and restricting calling volume to that node once a threshold level of failed calls is reached. However, the system disclosed in the '483 patent detects network overloads which have already occurred. As such, a telephone monitoring station (e.g., a Network Operations Center which monitors and controls network operations) employing the '483 system cannot take measures which will prevent a network from overloading. By the time the '483 system detects an overload, customers are already dissatisfied, revenues are already lost, and switching components may have already shutdown.
A need therefore exists for a system and method which allows potential mass addressing events to be identified so that preventative measures (which will reduce or eliminate the number of failed addressing attempts) may be undertaken. Within the telephone industry, such a system will substantially increase customer satisfaction by reducing failed calling volume and increase telephone service provider profitability by decreasing non-revenue generating calls (e.g., uncompleted, non-billable telephone calls).
It is therefore an object of this invention to provide an improved method of detecting mass addressing events.
It is a more particular object of this invention to detect potential mass addressing events and to alert a monitoring station of such potential events so that corrective measures may be taken prior to address routing circuitry (e.g., telephone network switches) overloading.